Current clinical diagnostics to appreciate the tumor location and spread involve digital rectal examination (DRE), total colposcopy with biopsy, abdominal sonography, thoracal X-ray, carcinoembryonic antigen (CEA) blood levels, and abdominal/thoracal computer tomography, and for rectum carcinoma, rigid rectoscopy, pelvic MR/CT, and rectal end sonography in case of locally limited tumors. Here, CEACAM5 is linked to rectal carcinoma.